The role of temporal distance of the events on the spatiotemporal dynamics of mental time travel to one's personal past and future

Abstract

Mental time travel to personal past and future events shows remarkable cognitive and neural similarities. Both temporalities seem to rely on the same core network involving episodic binding and monitoring processes. However, it is still unclear in what way the temporal distance of the simulated events modulates the recruitment of this network when mental time-travelling to the past and the future. The present study explored the electrophysiological correlates of remembering and imagining personal events at two temporal distances from the present moment (near and far). Temporal distance modulated the late parietal component (LPC) and the late frontal effect (LFE), respectively involved in episodic and monitoring processes. Interestingly, temporal distance modulations differed in the past and future event simulation, suggesting greater episodic processing for near as opposed to far future situations (with no differences on near and far past), and the implementation of greater post-simulation monitoring processes for near past as compared to far past events (with high demands on both near and far future). These findings show that both past and future event simulations are affected by the temporal distance of the events, although not exactly in a mirrored way. They are discussed according to the increasing role of semantic memory in episodic mental time travel to farther temporal distances from the present.

Figure 1

Stimuli and timing in a given experimental trial. Participants had up to 10 s to evoke a unique event related to the word cue (construction phase). They were asked to terminate the construction phase by pressing the spacebar as soon as they had generated the event, which led them to the elaboration phase (10 s long), in which they had to fill the event with as much detail as possible.

Figure 2

Electrophysiological data for the LPC time window. (a) Mean amplitude of the ERP averaged across the three electrodes selected for the LPC analyses (P3/4 and Pz). The grey rectangle shows the time window of this component (from 500 to 800 ms). (b) Far future vs near future comparison for the LPC, grey rectangle shows the cluster of time points for which the comparison was significant. For (a) and (b), shadowed regions indicate the standard error of the mean for each experimental condition. (c) Scalp map of the LPC for the mean average of all experimental conditions, showing the temporal course of this component.

Figure 3

Electrophysiological data for the LFE time window. (a) Mean amplitude of the ERP averaged across the three electrodes selected for the LFE analyses (F3/4 and Fz). The grey rectangle indicates the time window of this component (from 800 to 2000 ms). (b) Far past vs near past comparison for the LFE, grey rectangles show the clusters of time points for which the comparison was significant. For (a) and (b), shadowed regions indicate the standard error of the mean for each experimental condition. Panel (c) displays the temporal course of the LFE, averaged across conditions.